Heating system and control means therefor



Oct. 21, 1941. w. s. LANDON 2,259,645

HEATING SYSTEM AND CONTROL MEANS THEREFOR Filed July 11, 1938 3Sheets-Sheet l INVENTOR WK M /A(4 ATTORNEY A Oct. 21, 1941. w. s.LANDYON 2,259,645

HEATING SYSTEM AND CONTROL MEANS THEREFOR Filed July 11, 1958 aSheets-Sheet 2 INVENTOR way/J. MW

ZLMAK. HM

A4 ATTORNEY Oct. 21, 1941. w. s. LANDON 2,259,645

HEATING SYSTEM AND CONTROL MEANS THEREFOR Filed July 11, 1938 3Sheets-Sheet 3 I44 as I5 34 :5 I5" I I46 5b $UL WEI 12s FIG-5 W INVETORPatented Oct. 21, 1941 HEATING SYSTEM AND CONTROL MEANS THEREFOR WalterS. Landon, Detroit, Mich., assignor to Detroit Lubricator Company,Detroit, Mich., a corporation of Michigan Application July 11, 1938,Serial No. 218,720

17 Claims. (Cl. 2Q0-83) My invention relates generally to heatingapparatus including a liquid fuel burner, and more particularly to meansfor controlling the operation of the burner.

One of the objects of my invention is to provide an improved,electrically operated valve for controlling the flow of liquid fuel to aliquid fuel burner.

Another object is to provide an improved switching mechanism forcontrolling flow of fluid fuel to the burner, and to control the supplyof forced air so that the fuel can not be supplied without the air beingsupplied.

Another object is to provide a self-contained control apparatus forsupplying liquid fuel to an oil burner to maintain a substantiallyconstant temperature in a hot water tank.

Another object of my invention is to provide an improved switch meanswhich allows for quick, easy adjustment of the differential ofoperation.

The invention consists in the improved construction and combination ofparts, to be more fully described hereinafter and the novelty ofwhichwill be particularly pointed out and distinctly claimed.

In the accompanying drawings, to be taken as a part of thisspecification, I have fully and clearly illustrated my invention, inwhich drawings- Figure 1 is a view showing diagrammatically my controlapparatus installed in a hot water heating system;

Fig. 2 is a view showing a schematic diagram of the electrical circuitembodied in my invention, and its interrelation with an oil burner forheating water;

Fig. 3 is a top plan view of my apparatus with the top cover removed;

Fig. 4 is a view along the line l4 of Fig. 3 looking in the directionofthe arrows but "with the top cover in place;

Fig. 5 is'a view along the line H of Fig. 3, looking in the direction ofthe arrows but with the top cover in place;

Fig. 6 is a view along the line 9-4 of Fig.5.

showing only the electrical control apparatus and its supporting block;

Fig. 7 is a view along the line of Fig. 3 looking in the directionof thearrows;

Fig. 8 is an enlarged plan view of the switch means as seen in Fig. 4;

Fig. 9 is an enlarged detail view in section of a thrust spring and itscooperating parts, and

v Fig. 10 is a side view of the bowed thrust spring 65 in an inertposition apart from the rest of the apparatus.

Referring to the drawings by characters of reference the numeral Irepresents a chambered casing having an open top wall 2 over which acover member 3 is secured, as by means of screws 4. The cover member 3has a tubular, upwardly extending portion 5 which forms a chamber 6having side walls 1, 8 and end walls 9, ID. The bottomwall of thechamber 6 is formed by a plate l2held, as with screws Hi, to the member3. The upper wall of the chamber 6 is formed by part of a cover memberl5 secured by screws l5 threaded into a pair of bosses l5 projectinginwardly into chamber 6 from the walls I, 9. The cover member l5 hasadownwardly extending portion it which forms the side walls of a secondchamber I 1 located on top of the cover member 3 of the casing I. Thechamber II has a portion of the cover member 3 for its bottom wall and aportion of the cover member l5 for its top wall. The end wall 9 of thechamber 9 forms an end wall of the adjacent chamber l1 and separateschamber I! from the chamber 6. The opposite end wall of the chamber I!is formed by an upwardly extending portion I1 of an L-shaped angle piecel'l secured by one of each of the screws 4 and I3 to the cover member 3.The portion I'I' has a pair of apertures therethrough each of whichreceives a BX terminal fitting I1. The portion ll at the top thereofcarries a threaded lip ll which receives a screw IT. for securing thecover member l5 thereto. Secured to the bottom wall of easing I is astrainer chamber l9 having an inlet means l9 connected by means of aconduit member 29 to a suitable source of liquid fuel supply (notshown). The chamber It has an outlet 2| leading to a constant levelchamber 22 within the casing I, and ,the flow of fluid through theoutlet 2| into chamber 22 is controlled by means of a float valve 23which maintains a predetermined constant liquid level within chamber 22,along theline L-L.

A, U-shaped electric magnetic means 24 is located within chamber 6 andcomprises a laminated core 29 having one leg 29 secured by means ofscrews 21 to the plate I2- The other leg 28 of the'core 2! is spacedabove leg 26 and car ties an electrical coil 29 which surrounds and isconcentric therewith. Lead wires 39, 3| connect the coil 29 to bindingposts 32, 33 located in a molded block 34 made of suitable material,such as Bakelite, and which block 34 is to be hereinafter described. Thecoil 29 is operable to induce a magnetic flux inthe core 25 so that alaminated armature 35 having one end hinged at the open end of the leg26 is operable upon energization of the coil 29 to pivot so that theother end of the armature 35 will be'urged into engagement with the openend of the leg 28 to close the magnetic circuit between the open ends ofthe legs 26, 28. The armature 35 has a portion 36 which extends upwardlytoward the top wall portion of the cover member l5.

A bell crank lever 31 is pivoted at the intersection 38 of itshorizontal arm 39 and its vertical arm 48 by a pin 4| which is receivedwithin an aperture through and secured to the lever 31, as by peening42. The pin 4| is journaled in a boss 43 projecting inwardly into thechamber 6 from the side wall 1, intermediate the end wall l8 andarmature 35. The leg or arm 39 of the bell crank lever 31 has its endportion rounded, as at 44, and received between shoulders 45, 46 of avalve member 41. The valve member 41 is located intermediate the boss 43and end wall 9 and extends vertically downward through an aperture inthe plate |2 into the chamber 22. The lower end of the valve member 41cooperates with an outlet means 48 of the chamber 22 to control flow offluid from the chamber 22 by reason of its vertical 'spacing relative tothe outlet means 48.

- The outlet means 48 is connected by a conduit means 49 to a liquidfuel burner 58, as shown in' The upper end of the valve member 41.-

Fig. 1. is guided for reciprocal movement within an aperture in aninternal boss 52 projecting inwardly into chamber 6 from the sidewall 1. A pair of stop members 53, 54 are adjustably held in the boss 52and cooperate with the valve member 41 to limit upward and downwardmovement respectively thereof relative to the outlet means 48 andthereby limit the maximum and minimum flow respectively of fluid fromthe chamber 22.

Projecting from the wall 8 and extending inwardly therefrom into chamber6 is a boss 55 having rigidly secured thereto, as by screws 55, anupwardly extending carrying member 56 which extends substantiallyparallel to the arm 48 of the bell crank lever 31.v A horizontallyextending lever member 51 has one end 58 fulcrumed within an aperture inthe carrying member 56 and has the other end 59 loosely received withinan aperture in the arm 40. The lever member 51 has an aperture midwaybetween its ends 58, 59'

which receives one end 68 of a rod member 6|. The other end 62 of therod member 6| is re-i ceived within an aperture in the upwardlyextending portion 36 of the armature 35. Clips 63 which are secured inspaced positions by a convenient method on the rod member 6|, such asbeing in grooves, limit separating movement between the lever member 51and extended portion 36, which are urged in a separating direction by ahelical coil, thrust spring 64 surrounding and longitudinal of themember 62 and having its 0pposite ends abutting the memberv 51 andportion 36. The spring 64 transmits the thrust of the armature extendedportion 36 to the lever member 51 and exerts sufiicient opposing orseparating force between the lever member 51 and portion 36 so that uponmovement of the armature 35 by the coil 29, toward the lever member 51,the bell crank lever 31 will be pivoted upon its pin 4| and the valvemember 41 will be moved into engagement with its stop member 53. Theforce opposing movement of the bell crank lever 31, upon engagement ofvalve member 41 with its stop member 53, is now greater than the forceexerted by the spring 64, and further movement of the armature 35 intoabutting relation with leg 28 is accomplished by compressing the spring64 which provides lost-motion between the magnetic means 24 and thevalve 41 so that the armature 35 will abut the magnet leg 28. The

spring 64 is given a permanent set, see Fig. 10,

so that when oil the rod 6| and inert, it is bowed or curvedlongitudinally, preferably having its longitudinal axis in the form ofan arc. The lateral deflection or bowing of the spring is sufficient sothat when placed on or sleeved over the rod 6|, as in Fig. 9, the springis tensioned laterally of the rod axis engaging the rod on one side atspaced points and engaging the rod on the other side at an intermediatepoint. The spring is therefore held in frictional engagement with therod and opposes movement of the rod through its bore so that when placedin position on the rod member 6| the spring acts as an anti-rattlingmeans. The rod member 6|, when the valve is in open position, would, ifnot for the spring 64, merely lie loosely in the aperture through themember 51 and portion 36 and any vibration which might be caused by themagnetic means 24 would rattle the rod member 6| to cause an objectionalnoise. The spring 64 due to its tendency to assume the shape of an'arc,frictionally engages the rod member 6| and as the spring 64 itself isheld between the member 51 and portion 36, effectively holds the rodmember 6| against vibration. Another feature. of this construction isthe increased tendency of the spring 64 to prevent vibration, because ofthe increase in the frictional force due to the compression of spring64, at the time that the tendency of the rod member 6| to'vibrate isgreatest, or when the ,magnetic means 24 is urging the valve 41 in avalve opening direction. The end 58 of the lever member 51 is held infixed position by the carrying member 56, and the end 59 moves the bellcrank lever 31 with a force equal .to one-half that exerted by themagnetic means 24 but through a distance equal to twice that of the tendoutwardly from vertical edges thereof and are secured by means of screws12 through the wall 9, and the supporting member 66 is held by thescrews 12 in fixed relation to the wall 9. The switch means 65 comprisesa temperature sensitive power element 13, a switch arm 14 movablebetween contact members 15, 16 and 11 to' be hereinafter described morefully, and a stop means 18 limiting movement of the switch arm 14. Thestop means 18 comprises a U-shaped carrying member 19 having itsparallel arms 88, 8| of unequal length and having one arm extending oneither side of the switch arm 14. The longer arm 8| of the member 19 isspaced vertically above the shorter arm and switch arm 14 and is securedat the open extended and of arm 8| to the lower end 82 of a pin member83. The pin member 83 extends upward through an aperture 84 extendingfrom a slot or recess 85 in the bottom wall 86 of the'supporting block34 carried by the supporting member 66, and extends above the top wall8101? the block 34 through an aperture in the cover member I5 toterminate, as at 88, exterior to the apparatus. The pin member 83 has anannular projecting shoulder 89 spaced from the lower end 82 and locatedwithin the aperture 84. The aperture 84 is of a substantially largerdiameter than the pin member shoulder 89. The lower end portion 99 ofthe aperture 84 is of reduced diameter to substantially fit and guidethe pin member 83 in its reciprocal movement. A metallic cylinder member9|, preferably molded in place at the time the block 34 is fabricated,substantially fits and is secured within the aperture 84 to the block34. The upper end portion 92 of thecylinder member 9| is internallythreaded for reception of an externally threaded cylindrical member 93having'a top end wall 94 with a central aperture therethrough. Theinternal diameter of the member 93 is of suiiicient magnitude to receivethe shoulder 89 of the pin member 83, and the upper portion of the pinmember 83 is guided by the aperture through the wall 94. The lower endportion 95 of the member 93 projects within the cylinder member 9| sothat the extreme lower end forms an adjustable abutment 96 for a discabutment member 91 held from lateral movement by the internal wall ofthe member 9|. The disk member 91 receives the 'pin member 83 through acentral aperture therethrough so that the member 91 is locatedconcentric with and intermediate the shoulder 89 and end 82 of the pinmember 83. A helical coil spring 98 is concentric with the pin member 83and is held under compression between the portion 99 and the disk-member91, urging the disk member against the abutment 96. A second helicalcoil spring 99 is located concentric with the pin member 83 and has oneend abutting the upper face of the shoulder 89 and the other endabutting the underside of the end wall 94 of the member 93. The spring99 preferably exerts a force which is substantially equal to one-halfthat exerted by the spring 98 urging the disk member 91 against theabutment 96. Normally the pin member 83 is urged to the position shownin Fig. 4, but may be either raised or lowered with equal ease byraising or lowering the extending portion 88 which moves the arms 89, 8|relative to the switch arm I4. Upon release of the portion 88, themember 83 assumes its normal position, as shown in Fig. 4. By screwingthe cap member 93 in the cylinder member 9|, I can space the abutment 96'relative to the portion 99 and thereby change the normal position ofthe stop means I8 and the open position of the switch arm I4. Afteradjustment, the cap member 93 is locked in position by a locknut I99which is threaded to cap member. 93 and tightened against the upwardlyprojecting end wall of the cylinder member 9| to substantially preventmovement of the cap member 93 relative to the cylinder member 9|.

The switch means 65, which can be seen in Figs. '5, 6 and 8, has theswitch arm 14 and contact members I5, I6 and 11 carried within the slotor recess 85 of the block 34. The arm I4 is a channel-like member havinga flat base portion IIII and downwardly extending side portions I92. Thebase portion I9I has a longitudinally extending slot or aperture I93therethrough and has at one end portion a downwardly projecting lip I94.The lip I94 has a threaded aperture therethrough in which an adjustmentscrew I95 is threaded so that a conical end portion I96 thereof isextending beneath the base portion I9I toward the other end I9'I of theswitch arm I4. The end II" is pivotally supported by a spring I|5 uponcompression.

fulcrum rod member I98 which extends through an aperture in each of theside portions I92. The ends of the rod member I 98 are supported oneither side of the portions I92 in downwardly extending lugs I99 of aplate-like member II9 secured, as by screws III, to the bottom of therecess of the block 34. The plate-like member H9 is thereby insulatedfrom the casing I. The lugs I99 also serve to prevent lateral movementof the switch arm I4.

Intermediate the side portions I92 and below the base portion IIII is apivoted toggle lever member II2 which has one end portion pivoted on thefulcrum pin or rod member I98 and the other end portion extending towardthe lip I04 and being conical in shape, as at I I3. The conical portionI I3 extends toward the lip- I94 in substantial alignment with theaperture I93. The apex of the conical portion H3 is spaced from the apexof the conical end portion I96 of the screw I95, and a resilientlyurged, collapsibleexpansible toggle member II 4 having oppositelyextending, conical recessed end portions is under compressiontherebetween. One recess of the toggle member H4 is received by theconical end portion I I3 and the other recess is received by the conicalend portion I96. The toggle member I I4 is urged in an expansibledirection by a spring II5 which urges the conical portions II3, I96 in aseparating direction, and the pivoted toggle member H2 in a rotarymovement. The spring II5 exerts its force at such an angle on orrelative to the member II2 that upon clockwise movement (see Fig. 5) ofthe member||2 the component of force opposing movement will decreaseupon such clockwise movement even though the spring II5 which actsaccording to Hooks Law actually exerts a greater total force. It will beevident from the foregoing that the force of spring II 5 opposingmovement of the member II2 varies as the product of total force of thespring H5 and the sine of the angle between the line of the spring H5and a line connecting the portion I96 with the fulcrum pin I08 of thelever II 2. For small acute angles it will be noted that the sine willdecrease with greater rapidity than the increase of force of the I havefound that a spring having a rate of increase of force of 5 pounds perinch and acting through a maximum angle of 3 degrees will work in thisapparatus to give a satisfactory decrease in moment of force. The rotarymovement of the toggle member H2 is limited to the foregoing acute angleby a pair of adjustment screws II 6, II!

threaded in apertures through the member 2 so that upon initial movementof the member II2, the member II2 will move throughout its rangeofmovement due to the breakdown of the opposing force of the spring II 5.The screws I I6, I I 'I also locate the end points of travel of theconical end portion H3 in respect to the bottom ofthe recess 85 by theirengagement with the plate-like member III). The adjustment screw I95acts to determine the magnitude of force exerted by thespring H5 andthereby to determine the difierential of operation of the power elementI3.

The temperature sensitive power element I3 comprises a cap member II9having its open end portion I29 secured by means'of screws I2I to thelower face of the horizontally spaced side portion 68 of the channelmember 66. A bellows member I22 located within the cap member II9 hasone end secured in fluid-tight relation to the wall I23.

end portion I of the cap member and has the other end of the bellowsmember sealed to a reentrant movable end wall I23 located within the capmember II9 to form an expansible-collapsible chamber I24. A temperaturesensitive bulb I25 is connected by means of a suitable flexible, smallbore tubing I21 to the interior of the chamber I24 and a closed systemI28 is formed thereby. The system I28 is evacuated and charged with apredetermined quantity of temperature sensitive, volatile fluid so thatwith increasing temperature of the bulb I25 the pressure within chamberI24 will increase and urge the movable end wall I23 outwardly toward theopen end I20 of the cap member H9 with increasing force.

An internally threaded, cylindrical member I29 having an end wall I30 issecured in fluidtight relationship within a concentric aperture throughthe reentrant portion of the movable end The end wall I30 is within thechamber I24 and has a central aperture therethrough in which is sealedone end of a short piece of tubing I3I which is suitably closed at itsother end, externally of the member I29, subsequent to the tubing I 3Ibeing used for charging the system I28 with the volatile fluid. Themember I29 has a shoulder I32 within the chamber I24 which forms anabutment and guide for one end of a helical coil spring I33 held undercompression between the portion I32 and the inner end wall of cap memberH9. The spring I33 is operable in conjunction with the fluid pressure inchamber I24 to urge the wall I23 in an outward direction or toward thelever H2. The spring I33 is preferably one having a rate of forceincrease of 28 pounds per inch of length decrease. A screw-threaded,hollow thrust member I34 extends outwardly and is threaded into thecylindrical member I29 surrounding the tubing I3I, and carries at itsupward end a member I35 of electric insulating material. The member I 35carries a conical member I36 the apex of which is received in a conicalrecess in the lower wall of the pivoted member H2. The length of theupwardly extending thrust member I34 may be adjusted relative to themember I29 by screwing so that the upwardly extending conical endportion I36 is in proper space relation with the pivoted member I I2.

Rotational movement of the pivoted member I I2 by the upward movement ofthe thrust member I34 is opposed by a downwardly extending thrust memberI31 of electric insulating material which has a conical end portion I38received within a conical recess I39 in the ,upper wall of the memberH2. The member H2 is electrically insulated by the member I35 and thrustmember I31, and the molded block 34, from the easing I to electricallyisolate the switch arm 14. The thrust member I31 is urged toward themember II2 by a helical coil range spring I40 held under compressionagainst the thrust member I31 by an adjustable abutment member Iscrew-threaded,-as at I42, in a nut member I43 secured within anaperture in the side portion 61 of the channel member 66 so that themember I is operable to be moved relative to the thrust member I31 tochange -the acting force of the spring I40. A suitable knob means I44carried by and removable with the cover ber I through a radiallyextending pin I45 extending from the member I M into a slot I46 of themeans I44. An upwardly extending stop member I5 has operative connectionwith mempin I46 cooperates with the pin I45 to limit rotation of themember I4I to less than 360. The downward force exerted by the springI40, which acts in opposition to the upward force exerted through thecylindrical member I29, may be adjusted externally of the apparatus bythe knob means I44 to change the temperature at which bulb I25 willrotate the pivoted member H2. A spring with an increase in force of 41pounds per inch decrease in length is satisfactory. The particularcharacteristics of the springs H5, I33 and I40 depend upon the magnitudeof the acute angle formed between the member H2 and a line joining theconical portion I06 to the fulcrum pin I08. The member H2 in thisinstance is arranged so that the spring I I5 engages the member I22 oneinch from the fulcrum pin I08 and the springs I33 and I40 and powerelement 13 engage the member II2 one-eighth inch from the fulcrum pinI08. The springs are so arranged that the moment of force exerted by thespring II5 decreases more rapidly than the algebraic sum of the momentsof force caused by the decrease of force of spring I33 and increase offorce of spring I40, the resilience of the bellows I22 being taken intoconsideration as part of the spring I33.

The contact members 15, 16 are positioned above the arm 14 and arecarried by one end of current conducting spring members I41, I48respectively. The spring members I41, I48 are secured adjacent to but inspaced relation with the bottom of the recess at the end opposite to thecontact members 15, 16 to binding post members I49, 32 which arepreferably molded into the block 34. The contact member 11 is carriedbelow the switch arm 14 by a U-shaped current conducting, supportingmember I5I having a pair of parallel arms I52, I52 One parallel arm I52is attached to the post member I49 and the other parallel arm I52 towhich the contact member 11 is secured, extends below the switch arm 14.The switch arm 14 is connected by a lead wire I53 to a binding postmember I54 molded in the block 34. An electric conducting strip I55 alsomolded within the block 34 connects a binding post member I56 tothebinding post member 33 to which the lead wire 3| is fastened.

When the switch arm 14 is in the position shown in Fig. 5, the switcharm will be in engagement with contact members 15, 16. The conicalportion I I3 is held from further counterclockwise rotational movementby the adjustment screw H1; and the force of the spring II5 of thecollapsible-expansible toggle member I I4, acting between the portionI06 and member. II2, will flex the spring members I41, I48 until thecontact carrying ends thereof are in engagement with the bottom wall ofthe recess 85. This flexion of the spring members I41, I48 will occurafter contact has been made by the switch arm 14 and will cause a wipingaction between the contact members 15, 16 and the adjacent surface ofarm 14 and insure a good electrical contact therebetween. As the pivotedtoggle member H2 is rotated in a clockwise direction by the powerelement 13, the conical end portion II3 thereof will pass the line ofcenters between the conical portion I06 carried by-the switch arm 14 andthe fulcrum rod member I08, and the arm 14 will move in acounterclockwise direction with increasing velocity due to the expansiveforce of the toggle member H4. The spring members I41, I48 will followthe movement of the switch arm, 14 due to the resilient force urging thecontacts to their spaced position from the bottom wall 86, and will keepthe contact members I5, IS in electrical contact with the switch arm 14until the arm has gained speed enough to make a quick break with thecontacts.

The arm I4 is stopped in its opening movement and is prevented fromengaging the contact member II by the engagement of the arm I4 with theunderlying arm 80 of the stopmeans I8. The switch then normally remainsin open circuit position until closed by the spring I40 acting inopposition to the power element I3. Should it be desired to close thecircuit through contact member TI, it is necessary to push downward theportion 88 of the pin member 83. The arm 80 against which the arm I4 isurged by toggle member H4 is thereby lowered and the arm I4 is permittedto move into engagement with the contact member 11 under the expansiveforce of the toggle member II4. Upon release of the portion 80, thespring 90 will move the stop arm 80 to its normal position above that ofcontact member 11 to open the circuit between contact arm 14 and themember 11. Should it be desired that the circuit between arm I4 andcontact members I5, I6 be closed and the switch arm I4 is in opencircuit position, due to the power element I3, the

portion 88 may be raised manually so that the arm 80 will lift the armI4 against the force of the toggle member II4 into contact makingposition. Release of the pin member portion 88 will on use the arm 80 tobe moved to its normal position by the spring 99, and the toggle memberI I4 will then be effective to urge the arm "to open circuit position.

Now let us assume that the switch arm I4 is in the position shown inFig. 5, that is, with the temperature sensitive bulb I25 at a lowertemperature than the predetermined temperature for which the switch isset to open the circuit between switch arm I4 and contacts I5, I6. Theswitch arm I4 can now be moved manually from contact members 15, Hi toopen the circuits therebetween by depressing the portion 88. The armwill engage the switch arm I4 and move it against the force of thetoggle member II4. Further movement of the portion 08 downward will movethe switch arm I4 into circuit making relation with the contact member11. Release of the portion 88 will allow spring 08 to move the stop arms80, BI to normal position and the expansible toggle member II4 will movethe arm 14 to contact making position with contact members I5, I0.

The application of the apparatus described may be seen from thediagrammatic view of a water heating system shown in Fig. 1. The numeral200 represents generally my apparatus hereinbefore described, suppliedwith electrical energy through lead wires 2!, 202 connected to asuitable source of supply. An electric air supplying means 203 issupplied with electrical energy by lead lines 204, 205 connected to theswitch means of the apparatus 200. The output of air from the means 203is directed through a conduit means 206 to the liquid fuel burner 50,supplied with a suitable liquid fuel by the conduit means 40 from theapparatus 200. The heat output of the burner 50 is directed toward asuitable hot water tank 201 connected into a suitable hot water system(not shown). The temperature sensitive bulb I25 is located within asuitable bulb well 208 in heat exchange relation with the water in thetank 201 and is connected by the small bore tubing I2I to the apparatus200.

The schematic view shown in Fig. 2 in which like parts to other figuresare designated by the same numerals shows clearly the electrical circuitof my apparatus 200 connected to the equipment described in connectionwith Fig. 1. Lead wire MI is connected directly to the binding postmember I49 and thereby to the connected contact members I5, I1. Theother lead wire 202 from the electrical supply is connected to theterminal post I56. The lead wire 205 is connected to the post I56 and tothe electric air supplying means I03, and the other lead wire 204connected to the supplying means 203 is connected at its opposite end tothe terminal post I54 which is electrically connected to the switch arm14. The terminal post 33 is connected to one lead wire 3i of themagnetic coil 29 and the other lead wire 30 of the coil 29 is connectedto the terminal post 32 and therethrough to the directly connectedcontact member 16. In connecting my equipment in this manner to theswitch means, I substantially prevent the undesirable circumstance ofhaving the oil valve 41 held open by the magnetic means 24 and the airsupply means 203 deenergized. Each means 24, 203 is supplied directly bythe lead Wire 202. The lead wire 204 connects the means 203 directly tothe switch arm I4. The lead wire 20I is directly connected to thecontact members I5, 11 and the means 24 is directly connected by leadwire 3I to the contact member I6. If

the switch arm 14 is. in any contact making relation with members 15 orH, the circuit through.

in circuit making relation with wire 20I, the.

means 203 is electrically connected to the supply, and as the arm I4must be in contact with I members I5 or II to energize the magneticmeans 24, there is therefore no chance of having the valve member 41open without the air supply means 203 being energized, even though thecontacts should arc and stick together.

In operation my device works as follows: Assuming the water in tank 201to be at a lower temperature than the minimum predetermined temperaturefor which the apparatus 200 is set to operate, the fluid pressure in thesealed system I28 will be relatively low and the switch means 65 will bein the position shown in Fig. 5. The magnetic coil 29 will be energizedand holding the armature 35 against the leg 28. The valve member 41 willbe against its stop member 53 in maximum open position and the oil willflow through the conduit 40 from the chamber 22 and into the burner 50.The switch means 05 will also be making circuit through the electric airsupplying means 203 and the air requisite to insure proper operation ofthe burner 50 will be supplied. The heat output from the burner 50 isabsorbed by the water in tank 201 thereby raising its temperature. Whenthe predetermined maximum temperature for which the thermostatic switchmeans 65 is set to operate is reached, the pressure within the systemI28 will have increased sufficiently to force the movable wall I23outward from the cap member II! in opposition to the opposing force 01the spring I40. The pivoted toggle member II2 will upon initial movementby the power element 13 move throughout its range of movement withoutany additional increase in the force exerted by the element 13 due tothe breakdown of forces opposing movement of the member H2.v It will benoted that while the total force exerted by the spring H increases uponmovement of the member H2 in a clockwise direction (see Fig. 5) thecomponent of force of the spring H5 actually decreases due to the angleat which it acts on the member H2 and the moment of force exerted on themember H2 decreases. The decrease of moment of force must be greaterthan the algebraic sum of the decrease of moment of force of the springI33 and the increase in opposing force due to the collapsing of thebellows member I22 and of the spring I40. Upon movement of portion H3into the line of centers of portion I06 and the fulcrum pin or rodmember I08 moment of force of spring H5 exerted in opposition tomovement of the member H2 is zero and upon a slight further movement ofthe member H2 in theclockwise direction the moment of force exerted bythe spring H5 in fact acts to aid the power element in its movement ofthe memberH2. The additional aiding moment of force exerted by thespring H5 increases upon continued movement of the member H2 due to theangle of operation of spring H5 with respect to member H2 and is trueeven though the total force exerted by the spring H5 decreases uponspring-expansion. As the portion H3, portion I06 and .centerline of thespring H5 pass overcenter the spring which, of course, exerts areactionary force in the opposite direction of an equal magnitude tothat exerted in the first direction acts to move the switch arm 14 in acounter-clockwis direction (see Fi 5) a with an increasing force andconsequently increasing arm velocity due,to the change in angle at whichthe force of the spring H5 acts on the switch arm 14. Not only does thepresent construction allow for'a quck break due to the increase in theforce exerted by the spring H5 on the arm 14. but also the springmembers I41, I48 act to move the contact members 15, 15 respectivelyagainst the arm 14 until the arm 14' is travelling at a high rate ofspeed thereby preventing excessive arcing when the contact members partdue to a prolonged positioning of the contact members 15, 16 in arcingrelation with the arm 14.

' As was stated hereinbefore the thermo sensitive bulb I25, responsiveto the temperature of the controlled medium, is connected for purposesof convenience by a small bore or capillary tube I21 to the powerelement 13. As the power element 13 moves the member H2, the volume ofthe chamber I24 increases and if the pressure therein is to remainconstant or in balance with the pressure of the volatile fluid withinthe bulb I25 additional fluid must be supplied thereto from the bulb I25and this additional fluid must pass through the capillary tube I21.Movement of a quantity of fluid through a small bore or capillary tuberequires an elapse of time and therefore the "bellows member I22 cannotimmediately with a rapid movement move from its switch closed positionto its switch open position but must move with a relatively slowermovement depending upon the rate of breakdown of the chamber i24'corresponding to the predetermined high pressure in bulb I25 caused bythe predetermined maximum temperature for which the switch means is setto operate.

The power element 13 andmember H2 it is seen operates with a snap actioninsofar as the forces having once started movement, the members will notagain come into equilibrium until they have moved into their finalposition but the movement is of a relatively slow action when viewedwith the speed at which the arm 14 moves through its range of movement.The spring H5 has no time lag in its operation and will act to move theswitch arm 14 with a substan tially instantaneous movement for fastswitch operation. The construction embodied therefore has the advantageof a quick breaking switch mechanism while still retaining the use of 'asmall bore tubing which is flexible and: easily handled. The pivotedtoggle member H2 therefore rotates clockwise with a slow-snap action andthe switch arm 14 opens the circuits to the magnetic coil 29 through thecontactmember 16 and to the air supplying means 203 through contact 15with a fast snap action. The armamember 54 is preferably set to delivera minimum flow of fuel to the burner 50 so that proper combustiontherein with air being supplied by natural convection will occur and theburner 50 will stay ignited. The heat output under this condition ispreferably sufiicient to maintain the water at the given predeterminedtemperature, but suificiently low so that there is no danger of thewater becoming too hot.

As there becomes a demand for hotwater from the system, the burner 50under minimum fuel flow conditions is unable to maintain the water abovethe predetermined minimum temperature for which the apparatus is set toopen. As the water temperature drops, the bulb temperature alsodecreases with a decrease of the pressure in the closed system I28,until the force exerted by spring I40 overcomes the opening force of theend wall member I23. The pivoted toggle member H2 will thenrotatecounterclockwise causing the switch arm 14 to rotate with a snap actionclockwise into circuit making position with the contact members 15, 16to energize the air supplying means 203, which will then supply therequired extra air to the burner 50. The coil 29 also being energized,the armature 35 will be drawn toward the leg 28 and the valve member 41will be lifted by the bell crank lever 31 against its upper stop member53 to increase the flow of fuel to the burner 50. The valve member 41preferably engages its stop member 53 before the armature 35 engages theleg 28 and thereby is prevented from further movement in an opendirection. The bell crank lever member 31"is prevented from furthercounterclockwise rotation and the spring 64 compresses under the closingforce of the magnetic means 24 and operates as a lost-motion means toallow the armature 35 to engage the magnet leg 28. Engagement of thearmature 35 and leg 28 is necessary to prevent the armature fromvibrating under the influence of the coil 29 and causing a hummingnoise.

The difierential temperature necessary to operate the switch may beadjusted by screwing the cylinder member 93 in the member 9|- to raiseor lower the abutment 96, which causes the switch arm 14 to stop itsmovement in an open circuit direction closer or further away from theline of center of the conical portions I06, 3 and fulcrum rod member I08so that the movement of force exerted by the expansible-contractibletoggle member H4 is lessened or increased to demand a correspondingchange in pressure with the system I28 to exert the necessary force onthe thrust member I34. This adjustment is usually made upon manufactureof the apparatus. The only adjustment designed to be made in the fieldis the range adjustment controlled by the knob means I, and which may beadjusted by rotation of the knob means to increase or decrease the forceof the spring I40.

What I claim and desire to secure by Letters Patent of the United Statesis:

1. In an apparatus of the character described;

- a plurality of contact members, a movable contact arm cooperable withone of said members for completing an electrical circuit, stop meanslimiting movement of said arm prior to engagement thereof with a secondof said contact members, and means for moving said stop means so thatsaid arm is operable to close a circuit through said second contactmember.

2. In an apparatus of the character described, a plurality of contactmembers, a movable contact arm cooperable with a pair of said membersfor completing an electrical circuit therebetween, stop means limitingmovement of said arm prior to engagement thereof with another of saidcontact members spaced from and on the opposite side of said arm fromsaid pair of contact members, and manual means-for moving said stopmeans so that said arm is operable to close a circuit through saidanother contact member.

3. In an apparatus of the character described, a plurality of contactmembers, a movable contact arm cooperable with one of said members forcompleting an electrical circuit, a second of said contact members beingspaced from and on the opposite side of said arm from said one contactmember, a pair of spaced stop members located one on either side of saidarm and operable to allow engagement solely with said one contactmember, and means for moving said pair of stop members so that said armis operable to close a circuit solely through said second contactmember.

4. In an apparatus of the character described, a plurality of contactmembers, a movable contact arm cooperable with one of said members forcompleting an electrical circuit, stop means limiting movement of saidarm prior to engagement thereof with a second of said contact members,means for adjusting the position of said stop means comprising a pinmember, an abutment member operable to engage an abutment to limitmovement by said abutment member of said pin member in one direction,and resilient means 7 urging said abutment member into engagement withsaid abutment, said adjusting means being operable upon movement inopposition to said resnient means to move said stop means.

5. In an apparatus of the character described,

a plurality or contact members, a. movable contact arm cooperable withone of said members for completing an electrical circuit, stop meanslimiting movement of said arm prior to engagement thereof with a secondof said contact members, means for adjusting the position of said stopmeans comprising a pin member having a shoulder thereon, an abutmentdisk member having a central aperture therethrough receiving said pinmember, said shoulder abutting said disk member, an abutment meansoperable to be engaged by and to limit movement of said disk member inone direction, resilient means operable to urge said disk member intoengagement with said abutment means, and resilient means urging saidShoulder into engagement with said disk member.

6. In an apparatus of the character described, a plurality of contactmembers, a movable contact arm cooperable with one of said members forcompleting an electrical circuit, stop means limiting movement of saidarm prior to engagement thereof with a second of said contact mem-'bers, means for adjusting the position of said stop means comprising apin member having a shoulder thereon, a disk abutment member having acentral aperture therethrough receiving said pin member, said shoulderforming an abutment for said abutment member, an abutment means operableto be engaged by and to limit movement of said abutment member in onedirection, resilient means operable to urge said abutment member intoengagement with said abutment means, and resilient means urging saidshoulder into engagement with said abutment member, said first-namedresilient means acting with a force equal to twice that of saidsecondnamed resilient means so that said pin member resists movement ineither direction with the same'force.

7. In an apparatus of the character described, a plurality of contactmembers, a movable contact arm cooperable with one of said members forcompleting an electrical circuit, stop means limiting movement of saidarm prior to engagement thereof with a second of said contact members,means for adjusting the position of said stop means comprising a pinmember, an abutment member operable to engage an abutment to limitmovement by said abutment member of said pin member in one direction,resilient means urging said abutment member into engagement with saidabutment, said adjusting means being operable upon movement inopposition to said resilient means to move said stop means, and meansoperable upon movement of said stop means to urge said arm intoelectrical circuit making position with said second contact member.

8. In a device of the character described, a supporting member, a rodcarried by said supporting member, a pair of plate-like lever membershaving flanged edge portions, said edge portions having alignedapertures for receiving said rod and pivotally supporting said levermembers in overlying relationship, an abutment member on one of saidlever members and extending toward said rod, an abutment member on theother of said lever members facing said one lever member abutment andextending away from said rod, means limiting pivotal movement of saidone lever member in one direction, means for limiting movement of saidother lever member in one direction, spring means interposed undercompression between said abutment members and acting upon movement ofeither of said abutment members through a line connecting said rod andthe other or said abutment members to move the stationary one of saidlever members.

a. In a device or the character described, a supporting member, a. rodcarried by saiusupporting member, a pair or plate-like lever membershaving flanged edge portions, said edge portions having alignedapertures for receiving said rod and pivotally supporting said levermembers in overlying relationship, one of said lever members having anaperture therethrough, an abutment member on said one lever member andextending toward said rod, an abutment member on the other of said levermembers facing said one lever member abutment and extending away fromsaid rod, means limiting pivotal movement of said one lever member inone direction, means for limiting movement of said other lever member inone direction, spring means interposed under compression between saidabutment members and operable upon relative movement of said levers topass through said aperture, said spring means acting upon movement ofeither of said abutment members through a line connecting said rod andthe other of said abutment members to move the stationary one of saidlever members.

10. In an apparatus of the character described,

a supporting member having an aperture there through, a plate memberpositioned against the underface of said supporting member and having anaperture therethrough in alignment with said first-named aperture, afulcrum member carried by said plate member, a first lever memberfulcrumed on said fulcrum member and extending along said underface, anabutment carried by said first lever member spaced from and facing saidfulcrum member, a second lever member fulcrumed on said fulcrum memberand having a portion underlying said apertures, an abutment carried bysaid'second lever member and facing said first-named abutment, forceexerting means held under compression between said abutments, a powerelement carried by said supporting member and spaced outwardly from saidunderface and having a force exerting portion in engagement with andoperable to urge said second lever member in one direction, forceexerting means carried by said supporting member and having a portionextending through said apertures and engaging said second lever member,said lastnamed force exerting means-being operable to urge said secondlever member in a second direction against the force exerted by saidelement. and stop means limiting movement of each of said lever membersin said one and said second directions, said stop means and said elementand each of said force exerting means being so interrelated and arrangedthat the force exerted by said element necessary for initial ,movementof said second lever member will move said. second lever membercompletely through its range of movement in said one direction and willmove said first lever member in said second direction.

11. In an apparatus of the character described, a supporting memberhaving an aperture therethrough, a plate member positioned against theunderface of said supporting member and having an aperture therethroughin alignment with said first-named aperture, a fulcrum member carried bysaid plate member, a first lever member fulcrumed'on said fulcrum memberand extending along said underface, an abutment carried by said firstlever member spaced from and facing said fulcrum member, a secondlevermember fulcrumed on said fulcrum member and having a portion underlyingsaid apertures, an abutment carried by said second lever member andfacing said first-named abutment, force exerting means interposedbetween said abutments and exerting an expansive force, a power elementcarried by said supporting member and spaced force exerting portion inengagement with and operable to urge said second lever member in onedirection, force exerting means carried by said supporting member andhaving a portion extending through said apertures and engaging saidsecond lever member, said last-named force exerting means being operableto urge said second lever member in a second direction against the forceexerted by saidelement, a pair of stop members carried by said secondlever member one on each side of said fulcrum member, one of said pairof stop members being operable upon movement of said second levermemberin said one direction to engage said plate member to limit movement of,said second lever member in said one direction, the other of said pairof stop members being operable upon movement of said second lever memberin said second direction to engage said plate member to limit movementof said second lever member in said second direction, and means limitingmovement of said first lever member in said one and said seconddirections. v

12. In an apparatus of the character described, a supporting memberhaving an aperture therethrough, a plate member positioned against theunderface of said supporting member and having an aperture therethroughin alignment with said first-named aperture, a fulcrum member carried bysaid plate member, a first lever member fulcrumed on said fulcrum memberand extending along said underface, an abutment carried by said firstlever member spaced from and facing said fulcrum member, a second levermember fulcrumed on said fulcrum member and having a portion underlyingsaid apertures, an abutment carried by said second lever member andfacing said first-named abutment, force exerting means held undercompression between said abutments, a power element carried by saidsupporting member and spaced outwardly from said underface and having aforce exerting portion in engagement with and operable to urge saidsecond lever member in one direction, force exerting means carried bysaid supportingmember and having a portion extending through saidapertures and engaging said second lever member, said second-named forceexerting means being operable to urge said second lever member in asecond direction against the force exerted by-said element, said secondlever member having a pair of threaded apertures extending therethroughand opening toward said plate member, one of said threaded aperturesbeing on one side of said fulcrum member, the other of said threadedapertures being on the other side of said fulcrum member, a firstabutment member threadedly secured in said one threaded aperture andhaving a portion extending toward said plate member, a second abutmentmember threadedly secured in said other threaded aperture and having aportion extending toward said plate member, said first abutment memberportion being'operable upon movement of said second lever member in saidone direction to engage said plate member to limit movement of said sec-1 13. In an apparatus of the character described, a channel memberhaving a pair of substantially parallel walls, a supporting membercarried by said channel member and having spaced substantially parallelwalls one adjacent each of said channel parallel walls, said supportingmember having a recessed portion in one of said supporting memberparallel walls, a fulcrum carrying member positioned within saidrecessed portion and secured to said supporting member, a fulcrumcarried by said fulcrum carrying member, a pair of lever membersconcentrically fulcrumed on said fulcrum and positioned within saidrecessed portion, one of said lever members. being apertured so that theother of said lever members is operable to pass through said apertureupon rotational movement, said channel member parallel walls and saidsupporting member having aligned apertures opening into said recessedportion, a power element positioned against the one of said channelmember parallel 'walls adjacent said recessed portion and having a forceexerting portion extending through said one channel member wall apertureand operably engaging said other lever member, a movable abutment memberadjustably carried by the other of said channel member parallel wallsand having a portion extending through said other channel wall aperture,resilient means having a portion within said supporting member apertureand acting to exert a force to urge said other lever member inopposition to the force exerted by said power element, said movableabutment member being operable to control the force exerted by saidresilient means, overcenter means operatively connecting said levermembers and operable to be moved overcenter upon movement of said otherlever member in one direction, said overcenter means being operable uponmovement overcenter to move said one lever member in a second directionwtih 'a quick movement, and means operable by said one lever member-uponmovement thereof in said second direction. I

14. In an apparatus of the character described, a channel member havingapair of substantially parallel walls, a supporting member carried bysaid channel member and having spaced substantially parallel walls oneadjacent each of said channel parallel walls, said supporting memberhaving a recessed portion in one of said supporting member parallelwalls, a fulcrum member positioned within said recessed portion, a pairof lever members concentrically fulcrumed on said fulcrum member andpositioned within said recessed portion, one of said lever members beingapertured so that the other of said lever members is operable to passthrough said aperture upon rotational movement, said channel memberparallel walls and said supporting member having aligned aperturesopening into said recessed portion, a power element having a forceexerting portion extending through one of said channel member wallapertures and operably engaging said other lever vmember, means securingsaid element against the external surface of the one of said channelmember parallel walls having said one channel aperture and'operable tosecure said supporting member to the interior surface of said onechannel member parallel wall,

a movable abutment member adjustably carried by the other of saidchannel member parallel walls and having a portion extending throughsaid other channel wall aperture, resilient means having a portionwithin said supporting member aperture and acting to exert a force tourge said other lever member in opposition to the force exerted by saidpower element, said movable abutment member being operable to controlthe force exerted by said resilient means, overcenter means operativelyconnecting said lever members and operable to be moved overcenter uponmovement of said other lever member in one direction, said overcentermeans being operable upon movement overcenter to move said one levermember in a second direction with a quick movement, and means operable,by said one lever member upon movement thereof in said seconddirection.

15. In an apparatus of the character described, a channel member havinga pair of substantially parallel walls, a supporting member carried bysaid channel member and having spaced substantially parallel walls oneadjacent each of said channel parallelwalls, saidsupporting memberhaving a recessed portion in one of said supporting member parallelwalls, a fulcrum member positioned within said recessed portion, a pairof lever members concentrically iulcrumed on said fulcrum member andpositioned within said recessed portion,one of said lever members beingapertured so that the other of said lever members is operable to passthrough said aperture upon rotational movement, said channel memberparallel walls and said supporting member having aligned aperturesopening into said recessed portion, a power element positioned againstthe one of said channel member parallel walls adjacent said recessedportion and having a force exerting portion extending through said onechannel member wall aperture and operably engaging said other levermember, a movable abutment member adjustably carried by the other ofsaid channel member parallel walls and having a portion extendingthrough said other channel wall aperture, resilient means having aportion within said supporting member aperture and acting to exert aforce to urge said other lever member in opposition to the force exertedby said power element, said movable abutment member being operable tocontrol the force exerted by said resilient means, overcenter meansoperatively connecting said lever members and operable to be movedovercenter upon movement of said other lever member in one direction,said overcenter means being operable upon movement overcenter to movesaid one lever member in a second direction with a quick movement, meansoperable by said one lever member upon movement thereof in said seconddirection, said other channel member wall and said supporting memberhaving aligned apertures opening into said recessed portion, and meansextending through and movably positioned within said last-namedapertures and having a portion within said recessed portion operativelyengageable with said one lever member, said movably positioned meansbeing operable upon movement to move said one lever member irrespectiveof the position of said other lever member.

16. In an apparatus of the character described, a channel member havinga pair of substantially parallel walls, a supporting member carried bysaid channel member and having spaced substantially parallel walls oneadjacent each of said channel parallel walls, said supporting memberhaving a recessed portion in one of said supporting member parallelwalls, a fulcrum member positioned within said recessed portion, a pairof lever members concentrically fulcrumed on said 4 said other levermember, a movable abutment member adjustably carried by the other ofsaid channel member parallel walls and having a portion extendingthrough said other channel wall aperture, resilient means having aportion within said supporting member aperture and acting to exert aforce to urge said other lever member in opposition to the force exertedby said power element, said movable abutment member being operable tocontrol the force exerted by said resilient means, overcenter meansoperatively connecting said lever members and operable to be movedovercenter upon movement of said other lever member in one direction,said overcenter means being operable upon movement overcenter to movesaid one lever member in a second direction with a quick movement, meansoperable by said one lever member upon movement thereof in said seconddirection, and means held in a fixed plane spaced from said otherchannel member wall and rotatable therein to move said movableabutment'member.

17. In an apparatus of the character described, a plate member having anaperture therethrough. a fulcrum member carried by said plate member, afirst lever member fulcrumed on said fulcrum member and extending alongone face of said plate member, an abutment carried by said first levermember spaced from and facing said fulcrum member, a second lever memberfulcrumed on said fulcrum member and having a portion underlying saidaperture, an abutment carried by said second lever member and facingsaid first-named abutment, force exerting means held under compressionbetween said abutments, a power element spaced outwardly from said faceand having a force exerting portion in engagement with and operable tourge said second lever member in one direction, force exerting meanshaving a portion extending through said aperture and engaging saidsecond lever member, said last-named force exerting means being operableto urge said second lever member in a second direction against the forceexerted by said element, and stop means limiting movement of each ofsaid lever members in said one and said second directions, said stopmeans and said element and each of said force exerting means being sointerrelated and arranged that the force exerted by said elementnecessary for initial movement of said second lever member will movesaid second lever member completely through its range of movement insaid one direction and will move said first lever member in said seconddirection.

WALTER S. LANDON.

October 21, 19in.

Patent No. 2, 259, 6&5.

LANDON.

WALTER S It is hereby certified that error appears in the abovenumberedpatent requiring correction as follows; Page 1, second column,line 51, for "17" read "17 second column, strike out the ans 205-" for"means 105" read me present drawings and insert instead the followingline l2,

Oct. 21, 1941.

W. 5. LANDQN HEATING SYSTEM AND CONTROL MEANS THEREFOR Filed July 11.1938 3 Sheets-Sheet l INVENTOR Ham, 4!. WW BY M ATTORNEY Flo-3 06L 1941-w. s. LANDON HEATING SYSTEM AND CONTROL MEANS THEREFOR Filed July 11,1958 3 Sheets-Sheet 2 & m

may;

V iiibziiqn 0 A 3 A! 5 .1 Z I. e

INVENTOR m BY WK M 44", ATTORNEY Oct. 21, 1941. w. s. LANDON HEATINGSYSTEM AND CONTROL MEANS THEREFOR Filed July 1939 s Sheets-Sheet 3 m4 F1825 m 54 \5 |5 I45 1% b 14 I 30: If) 4 I Q, 5]

m 4 H 453 [011, go 105 1 J05 Q l I. 4-

' B M h i 18 an e 10a 17%;

INVENTOR J 1, ATTORNEY and that the said Letters Patent should be readwith this correction therein that the same may conform to the record ofthe case in the Patent Office.

Signed and sealed this 21th day of February, A. D. l9LL2.

Henry Van Arsdale,

(Seal) Acting Commissioner of Patents.

I CERTIFICATE OF CORRECTION.

Patent No. 2,259, 6L5.

October 21 19in.

LAN'DON.

WALTER S in the above numsecond bered patent requiring correction asfollows Page 1 column, line 51, for "17" read "17 page 5, second column,

for "means 105" read means 205"; strike out the present drawings andinsert instead the following line l2,

Oct. 21, 1941.

W. 5. LANDQN HEATING SYSTEM AND CONTROL MEANS THEREFOR Filed July 11.1958 I5 Sheets-Sheet l lure 7 INVENTOR M ATTORNEY FIG-3) 1941- w. s.LANDON HEATING SYSTEM AND CONTROL MEANS THEREFOR Filed July 11, 1938 3Sheets-Sheet 2 INVENTOR guavdf MW 4, ATTORNEY Oct. 21, 1941. w 5 LANDON2,259,645

SYSTEM AND-CONTROL MEANS THEREFOR HEATING Filed July 11. 1939 sSheets-Sheet s J4, ATTORNEY and that the said Letters Patent should beread with this correction therein that the same may conform to therecord of the case in the Patent Office.

Signed and sealed this 2mm day of February, A. D. 19m.

Henry Van Arsdale, Acting Commissioner of Patents (Seal)

